<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Number</title>
</head>
<body>
        <script>
            var n = new Number(10);         //可像纯数字一样参与运算
            console.log(typeof n);           //obj
            console.log(n instanceof Number);  //true

            var m = 20;
            console.log(n/m);
            var x = 12.333;
            console.log(x.toFixed(2));

        </script>
</body>
</html>